OSError: libgomp.so.1: cannot open shared object file: No such file or directory

TL;DR: lightgbm needs the OpenMP runtime library and your Linux box does not have it. Install the libgomp system package and the import works.

The error

OSError: libgomp.so.1: cannot open shared object file: No such file or directory

Fix it

1. Install the OpenMP runtime. On Debian/Ubuntu:

   sudo apt install libgomp1

   On RHEL/Fedora: sudo dnf install libgomp. Expected: package installs.

2. Verify the library resolves:

   ldconfig -p | grep libgomp

   Expected: a line showing libgomp.so.1.

3. Retry:

   python -c "import lightgbm; print(lightgbm.__version__)"

   Expected: prints the version.

4. Alternative: install lightgbm from conda-forge, which bundles the runtime:

   conda install -c conda-forge lightgbm

When this applies

Use this when import lightgbm on Linux raises the libgomp.so.1 error.

When it does not apply

On macOS the equivalent missing library is libomp.dylib (brew install libomp). If a different .so is missing, install that library instead.

Compatibility

Linux, lightgbm pip wheels that link the system OpenMP.

Root cause

lightgbm's compiled core links against libgomp for OpenMP parallelism. Minimal docker images and stripped servers often lack the libgomp runtime package, so the dynamic loader fails at import.

Edge cases

In docker, add the package to the Dockerfile so rebuilds do not regress. On clusters without sudo, the conda-forge build is the way out since it carries its own runtime.

The Ampel-HU-astro README (AmpelAstro/Ampel-HU-astro) documents this exact failure: importing lightgbm fails with OSError: libgomp.so.1: cannot open shared object file on systems without the OpenMP runtime. The documented fix is installing the libgomp system package (e.g. the libgomp1 OS package) so the shared library resolves, after which import lightgbm succeeds. Source: https://github.com/AmpelAstro/Ampel-HU-astro